After the proclamation, Union troops became an army of liberation as they advanced in the South. During the war, one out of every seven Confederate slaves (about 500,000) escaped to the Union army. The South was thus deprived of desperately needed labor to till fields, build forts and fix railroads.
The Emancipation Proclamation also paved the way for the enlistment of black Americans as soldiers. During the summer of 1862, as Lincoln pondered emancipation, the North was facing a shortage of soldiers. Lincoln even offered volunteers enlistments for only nine months instead of the usual three years, hoping that a shorter enlistment would attract more recruits. One solution: Enlist black Americans, whether free men from the North or freed slaves from the South.